Encapsulating film stacks for OLED applications

ABSTRACT

Embodiments described herein generally relate to a method and apparatus for encapsulating an OLED structure, more particularly, to a TFE structure for an OLED structure. The TFE structure includes at least one dielectric layer and at least two barrier layers, and the TFE structure is formed over the OLED structure. The at least one dielectric layer is deposited by atomic layer deposition (ALD). Having the at least one dielectric layer formed by ALD in the TFE structure improves the barrier performance of the TFE structure.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims is a continuation application of U.S. patentapplication Ser. No. 15/149,785, entitled “Encapsulating Film Stacks ForOLED Applications”, file May 9, 2016, which claims benefit of U.S.Provisional Application Ser. No. 62/161,760 filed May 14, 2015 and U.S.Provisional Application Ser. No. 62/172,784 filed Jun. 8, 2015, whichare incorporated by reference in their entirety.

BACKGROUND Field

Embodiments described herein generally relate to a method and apparatusfor encapsulating an organic light emitting diode (OLED) structure, moreparticularly, to a thin film encapsulation (TFE) structure for an OLEDstructure.

Description of the Related Art

Organic light emitting diode displays (OLED) have gained significantinterest recently in display applications in view of their fasterresponse times, larger viewing angles, higher contrast, lighter weight,lower power and amenability to flexible substrates. Generally, aconventional OLED is enabled by using one or more layers of organicmaterials sandwiched between two electrodes for emitting light. The oneor more layers of organic materials include one layer capable ofmonopolar (hole) transport and another layer for electroluminescence andthus lower the required operating voltage for OLED display.

In addition to organic materials used in OLED, many polymer materialsare also developed for small molecule, flexible organic light emittingdiode (FOLED) and polymer light emitting diode (PLED) displays. Many ofthese organic and polymer materials are flexible for the fabrication ofcomplex, multi-layer devices on a range of substrates, making them idealfor various transparent multi-color display applications, such as thinflat panel display (FPD), electrically pumped organic laser, and organicoptical amplifier.

OLED structures may have a limited lifetime, characterized by a decreasein electroluminescence efficiency and an increase in drive voltage. Amain reason for the degradation of OLED structures is the formation ofnon-emissive dark spots due to moisture or oxygen ingress. For thisreason, OLED structures are typically encapsulated by a buffer layersandwiched between barrier layers. The buffer layer is utilized to fillany voids or defects in the first barrier layer such that the secondbarrier layer has a substantially uniform surface for deposition. Thebuffer layer and the barrier layers may be fabricated from differentmaterials including organic materials or inorganic materials as neededfor different moisture resistance, film optical transparency and processrequirements. However, different materials, especially organic andinorganic materials, often have different film properties, therebyresulting in poor surface adhesion at the interface where the organicand the inorganic layers are in contact with. Poor interface adhesionoften allows film peeling or particle generation, thereby adverselycontaminating the device structure and eventually leading to devicefailure. Additionally, poor adhesion at the interfaces between theorganic and inorganic materials may also increase the likelihood of filmcracking, thereby allowing the moisture or air to sneak into the devicestructure, thereby deteriorating the device electrical performance.

Therefore, an improved method and apparatus for encapsulating an OLEDstructure is needed.

SUMMARY

Embodiments described herein generally relate to a method and apparatusfor encapsulating an OLED structure, more particularly, to a TFEstructure for an OLED structure. The TFE structure includes at least onedielectric layer and at least two barrier layers, and the TFE structureis formed over the OLED structure. The at least one dielectric layer isdeposited by atomic layer deposition (ALD). Having the at leastdielectric layer formed by ALD in the TFE structure improves the barrierperformance of the TFE structure while maintaining desired opticalproperties and film transparency.

In one embodiment, a TFE structure includes at least one dielectriclayer that is formed by an ALD process, and at least two barrier layers.

In another embodiment, an OLED device includes an OLED structure, and aTFE structure formed over the OLED structure. The TFE structure includesat least one dielectric layer that is formed by an ALD process, and atleast two barrier layers.

In another embodiment, a thin film encapsulation structure includes afirst barrier layer formed on a substrate having an OLED structure, afirst dielectric layer that is formed by an atomic layer depositionprocess disposed on the first barrier layer, a second barrier layerdisposed on the first dielectric layer, and a second dielectric layerdisposed on the barrier layer.

In yet another embodiment, a cluster system for manufacturing a thinfilm encapsulation structure for a OLED device includes a clusterprocessing system comprising a transfer chamber, a load lock chambercoupled to the transfer chamber, wherein the load lock chamber isconfigured to transfer a substrate in a quadrilateral form from anambient environment outside the cluster processing system to a vacuumenvironment inside the transfer chamber, and a plurality of processingchambers coupled to the transfer chamber configured to perform processeson the substrate, wherein the plurality of processing chambers includeat least a chemical vapor deposition chamber and/or a physical vapordeposition chamber and an atomic layer deposition chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentdisclosure can be understood in detail, a more particular description ofthe disclosure, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this disclosure and are therefore not to beconsidered limiting of its scope, for the disclosure may admit to otherequally effective embodiments.

FIGS. 1A-1F are schematic cross sectional views of an OLED structureencapsulated by a TFE structure according to various embodimentsdescribed herein.

FIGS. 1C′-1E′ are schematic cross sectional views of an OLED structureencapsulated by a TFE structure according to various embodimentsdescribed herein.

FIG. 2 is a flow diagram of a method for forming the TFE structure overthe OLED structure according to various embodiments described herein.

FIGS. 3A-3E illustrate schematic cross sectional views of an OLED deviceduring different stages of the method of FIG. 2.

FIG. 4 is a flow diagram of a method for forming the TFE structure overthe OLED structure according to various embodiments described herein.

FIGS. 5A-5D illustrate schematic cross sectional views of an OLED deviceduring different stages of the method of FIG. 2.

FIGS. 6A-6C are charts illustrating the benefit of having the TFEstructure shown in FIGS. 1A-1F.

FIG. 7 is a schematic, cross sectional view of a PECVD chamber that maybe used to perform the methods described herein.

FIG. 8 is a schematic, cross sectional view of an ALD chamber that maybe used to perform the methods described herein.

FIG. 9 is a schematic, cross sectional view of a PVD chamber that may beused to perform the methods described herein.

FIG. 10 is a schematic view of a multi-chamber substrate processingsystem including processing chambers described herein.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements and features of oneembodiment may be beneficially incorporated in other embodiments withoutfurther recitation.

DETAILED DESCRIPTION

Embodiments described herein generally relate to a method and apparatusfor encapsulating an OLED structure, more particularly, formanufacturing a TFE structure for encapsulating an OLED structure. TheTFE structure includes at least one dielectric layer and at least twobarrier layers, and the TFE structure is formed over the OLED structure.The at least one dielectric layer is deposited by atomic layerdeposition (ALD). The dielectric layer formed by ALD process has desiredfilm properties, such as relatively high film density as well as strongatomic bonding structures so that good moisture resistance, desiredoptical properties and the barrier performance of the TFE structure maybe obtained and improved.

FIGS. 1A-1F are schematic cross sectional views of an OLED structure 102encapsulated by a TFE structure 104 according to various embodimentsdescribed herein. As shown in FIG. 1A, the OLED structure 102 may bedisposed over a substrate 106, and a contact layer 108 may be disposedbetween the substrate 106 and the OLED structure 102. The TFE structure104 may include a first barrier layer 110 disposed on the OLED structure102, a dielectric layer 112 disposed on the first barrier layer 110, abuffer layer 114 disposed on the dielectric layer 112, and a secondbarrier layer 116 disposed on the buffer layer 114.

In one example, the substrate 106 may be made of glass or plastic, suchas polyethyleneterephthalate (PET) or polyethyleneterephthalate (PEN).The contact layer 108 may be made of silicon nitride (SiN) and/orsilicon oxide (SiO₂).

The first barrier layer 110 may be an inorganic layer, such as adielectric layer including silicon nitride (SiN), silicon oxynitride(SiON), silicon dioxide (SiO₂), aluminum oxide (Al₂O₃), aluminum nitride(AlN), or other suitable dielectric layer. In one embodiment, the firstbarrier layer 110 is a silicon nitride layer. The first barrier layer110 may be deposited by a suitable deposition technique, such aschemical vapor deposition (CVD), PECVD, physical vapor deposition (PVD),spin-coating, or other suitable technique. The buffer layer 114 may bean organic layer, such as a hexamethyldisiloxane (HMDSO) layer, forexample a fluorinated plasma-polymerized HMDSO (pp-HMDSO:F). The bufferlayer 114 may be deposited by a suitable deposition technique, such asPECVD. The second barrier layer 116 may be an inorganic layer, such as adielectric layer similar or identical to the first barrier layer 110,and the second barrier layer 116 may be deposited by a suitabledeposition technique, such as CVD, PVD, ALD, spin-coating, or othersuitable technique.

The TFE structure 104 includes at least one dielectric layer, such asthe dielectric layer 112, that is deposited by ALD. As shown in FIG. 1A,the dielectric layer 112 is disposed between the first barrier layer 110and the buffer layer 114. In the example wherein the first barrier layer110 is not present, the dielectric layer 112 may be formed on thesubstrate 106 or the contact layer 108 directly and in direct contactwith the OLED structure 102. The dielectric layer 112 may be aninorganic layer, such as an inorganic oxide layer, oxide layer, asilicon containing dielectric layer, a metal containing dielectriclayer, or a multiple layer stack of any combinations of dielectriclayers mentioned above or any suitable dielectric layer as needed. Inone example, the dielectric layer 112 may be Al₂O₃, titanium oxide(TiO₂), zirconium (IV) oxide (ZrO₂), aluminum titanium oxide (AlTiO),aluminum zirconium oxide (AlZrO), zinc oxide (ZnO), indium tin oxide(ITO), AlON, SiON, AlN or any suitable inorganic layers.

In some embodiments, the dielectric layer 112 may include compositestructures with multiple layers. The thickness of the dielectric layer112 may range from about 100 Angstroms to about 600 Angstroms, such asabout 300 Angstroms. It is believed that dielectric layer 112 formed byan atomic layer deposition (ALD) process may have film properties thatmay provide desired moisture resistance and film transparency. It isbelieved that the ALD process is enabled by a slow deposition processwith a first monolayer of atoms being absorbed and adhered on a secondmonolayer of atoms formed on a carefully selected substrate surface.Strong adherence of atoms in each layers and absorbability of the layersof atoms onto the surface of substrate provide compact and securedbonding structures in the film structures so as to render a filmproperty with a high film density (compared to a chemical vapordeposition process) that may efficiently prevent moisture or contaminantfrom penetrating therethrough. Furthermore, the slow ALD deposition rateof the dielectric layer 112 also allows the atoms from the dielectriclayer 112 to gradually fill in the pinholes, pores, pits or defects thatmay be occurred from the substrate surface (e.g., the first barrierlayer 110 in the examples of FIG. 1A) so as to assist repairing the filmdefects from the substrate surface. In contrast, the conventional plasmaenhanced chemical vapor deposition process (PECVD) often provides arelatively fast deposition process with high throughput but rendersrelatively porous film structures for the resultant film layer. Thus,when utilizing such porous film structures from a conventional PECVDprocess as a barrier or passivation layer in an encapsulating structure,undesired contaminant, dust, or moistures from the air or environmentoften have a relatively high likelihood of sneaking into the porousstructures or atomic vacancies in the deposited film layers, resultingin fast material structure degradation or film structure damage after aperiod of operation time. Thus, by utilizing the dielectric layer 112formed by the ALD process, a film layer with high density that may beefficiently obtained, serving as a moisture resistance layer to preventmoisture from the air or environment to penetrate into the underlyingOLED device 102 to undesirably alter the device performance. In theexample wherein high throughput of the manufacturing cycles is desired,a plasma assisted atomic layer deposition (PE-ALD) process may beutilized instead to provide a relatively higher deposition rate(compared to ALD or thermal ALD) of deposition process while stillmaintaining the desired degree of film density.

In one example, the dielectric layer 112 may also have a wettabilityhaving a water contact angle less than 60 degrees so as to facilitatethe layers subsequently formed thereon with high adhesion.

The dielectric layer formed by the ALD process may be disposed atdifferent locations within the TFE structure 104. For example, in theexample depicted FIG. 1B, the TFE structure 104 includes a dielectriclayer 118 disposed on the OLED structure 102, the first barrier layer110 disposed on the dielectric layer 118, the buffer layer 114 disposedon the first barrier layer 110, and the second barrier layer 116disposed on the buffer layer 114. The dielectric layer 118 may besimilar to the dielectric layer 112, and the dielectric layer 118 118 isalso formed by an ALD process.

In the example depicted in FIG. 1C, the TFE structure 104 includes thefirst barrier layer 110 disposed on the OLED structure 102, the bufferlayer 114 disposed on the first barrier layer 110, a dielectric layer120 disposed on the buffer layer 114, and the second barrier layer 116disposed on the dielectric layer 120. The dielectric layer 120 may besimilar to the dielectric layer 112, and the dielectric 118 depicted inFIGS. 1A and 1B respectively and the dielectric layer 120 is also formedby an ALD process. In the example wherein the buffer layer 114 has asmaller dimension that does not substantially cover the entire surfaceof the first barrier layer 110, a portion of the dielectric layer 120may be in direct contact with the underlying first barrier layer 110where the buffer layer 114 is not present, as shown in FIG. 1C′.Similarly, when the buffer layer 114 shown in FIGS. 1A and 1B also has asmaller dimension that does not substantially cover the entire surfaceof the dielectric layer 112 or the first barrier layer 110 respectively,a portion of the second barrier layer 116 may be in direct contact withthe underlying dielectric layer 112 or the first barrier layer 110 wherethe buffer layer 114 is not present.

As shown in FIG. 1D, the TFE structure 104 includes the first barrierlayer 110 disposed on the OLED structure 102, the buffer layer 114disposed on the first barrier layer 110, the second barrier layer 116disposed on the buffer layer 114, and a dielectric layer 121 disposed onthe second barrier layer 116. Similarly, in the example where bufferlayer 114 a smaller dimension that does not substantially cover theentire surface of the first barrier layer 110, a portion of the secondbarrier layer 116 may be in direct contact with the underlying firstbarrier layer 110 where the buffer layer 114 is not present, as shown inFIG. 1D′. The dielectric layer 121 may be similar to the dielectriclayer 112 depicted in FIG. 1A and the dielectric layer 121 is alsoformed by an ALD process.

In some embodiments, the TFE structure 104 may include multipledielectric layers that are formed by ALD processes. As shown in FIG. 1E,the TFE structure 104 includes the first barrier layer 110 disposed onthe OLED structure 102, the dielectric layer 112 disposed on the firstbarrier layer 110, the buffer layer 114 disposed on the dielectric layer112, the additional dielectric layer 120 disposed on the buffer layer114, and the second barrier layer 116 disposed on the additionaldielectric layer 120. The locations of the dielectric layers 112, 120are not limited to between the first barrier layer 110 and the bufferlayer 114 and between the buffer layer 114 and the second barrier layer116, respectively. Similarly, in the example where buffer layer 114 asmaller dimension that does not substantially cover the entire surfaceof the dielectric layers 112, a portion of the additional dielectriclayer 120 may be in direct contact with the underlying dielectric layers112 where the buffer layer 114 is not present, as shown in FIG. 1E′. Anycombination of the dielectric layers shown in FIGS. 1A-1E may besuitable for the TFE structure 104.

In some embodiments, the buffer layer 114 is not present in the TFEstructure 104. In some embodiments, the TFE structure 104 may include afirst barrier layer 122 disposed on the OLED structure 102, a firstdielectric layer 124 disposed on the first barrier layer 122, and asecond barrier layer 126 disposed on the first dielectric layer 124, asshown in FIG. 1F. The barrier layers 122, 126 may have a thickness ofabout 1200 Angstroms or less and the first dielectric layer 124 may havea thickness of about 600 Angstroms or less. In some embodiments, the TFEstructure 104 further includes a second dielectric layer 128 disposed onthe second barrier layer 126 and a third barrier layer 130 disposed onthe second dielectric layer 128, as shown in FIG. 1F. The barrier layers122, 126, 130 may have a thickness of about 800 Angstroms or less andthe dielectric layers 124, 128 may have a thickness of about 300Angstroms or less. Thus, the total thickness of the TFE structure 104with three layers 122, 124, 126 may be the same as the total thicknessof the TFE structure 104 with five layers 122, 124, 126, 128, 130. Thebarrier layers 122, 126, 130 may be similar to the barrier layer 110,and the dielectric layers 124, 128 may be similar to the dielectriclayer 112 depicted in FIG. 1A. The dielectric layers 124, 128 are formedby an ALD process. With alternating barrier and ALD formed dielectriclayers, the barrier performance of the TFE structure 104 with highmoisture resistance as well as high optical film transparency areobtained.

FIG. 2 is a flow diagram of a method 200 for forming the encapsulatingstructure 104 over the OLED structure 102 according to variousembodiments described herein. FIGS. 3A-3E illustrate schematic crosssectional views of an OLED device 300 during different stages of themethod 200 of FIG. 2. The method 200 starts at process 202 byintroducing the substrate 106 having the preformed OLED structure 102disposed thereon into a processing chamber. The substrate 106 may havethe contact layer 108 disposed thereon, with the OLED structure 102disposed on the contact layer 108, as shown in FIG. 3A.

At process 204, a mask 309 is aligned over the substrate 106 such thatthe OLED structure 102 is exposed through an opening 307 unprotected bythe mask 309, as shown in FIG. 3A. The mask 309 is positioned such thata portion 305 of the contact layer 108 adjacent the OLED structure 102is covered by the mask 309 so that any subsequently deposited materialdoes not deposit on the portion 305. The portion 305 of the contactlayer 108 is the electrical contact for the OLED device 300. The mask309 may be made from a metal material, such as INVAR®.

At process 206, the first barrier layer 110 is deposited on thesubstrate 106, as shown in FIG. 3A. The first barrier layer 110 has afirst portion 308 a and a second portion 308 b and a thickness ofbetween about 5000 Angstroms and about 10000 Angstroms. The firstportion 308 a of the first barrier layer 110 is deposited through theopening 307 onto a region of the substrate 106 exposed by the mask 309,which includes the OLED structure 102 and a portion of the contact layer108. The second portion 308 b of the first barrier layer 110 isdeposited on the mask 309 covering a second region of the substrate 106,which includes the portion 305 of the contact layer 108.

At process 208, after the first barrier layer 110 is formed on thesubstrate 106, the dielectric layer 112, such as an inorganic layer, isthen formed on the first barrier layer 110 on the substrate 106, asshown in FIG. 3B. A first portion 312 a of the dielectric layer 112 isdeposited on the substrate 106 through the opening 307 of the mask 309on the region of the substrate 106 exposed by the mask 309, covering thefirst portion 308 a of the first barrier layer 110. A second portion 312b of the dielectric layer 112 is deposited on the second portion 308 bof the first barrier layer 110 disposed on the mask 309, which coversthe portion 305 of the contact layer 108.

The dielectric layer 112 may be deposited by an ALD process, such asplasma assisted ALD or thermal ALD. Atomic layer deposition (ALD)process is a deposition process with self-terminating/limiting growth.The ALD process yields a thickness of only a few angstroms or in amonolayer level for each cycle of deposition. The ALD process iscontrolled by sequentially distributing chemical and reactant into aprocessing chamber which is repeated in cycles. The thickness of thedielectric layer 112 formed by the ALD process depends on the number ofthe reaction cycles. The first reaction provides a first atomic layer ofmolecular layer being absorbed on the substrate and the second reactionprovide a second atomic layer of molecular layer being absorbed on thefirst atomic layer.

In one embodiment, the dietetic layer 112 is an inorganic layer, such asan Al₂O₃ layer. The aluminum oxide (Al₂O₃) layer deposited has highthermal stability, good electrical resistivity, good moisture resistanceand high purity as well as maintaining a desired degree of filmtransparency, thus making the aluminum oxide (Al₂O₃) layer as a goodcandidate for use as a barrier/blocking layer in an encapsulatingstructure for OLED. Other similar inorganic layer (including metaldielectric layer), such as titanium oxide (TiO₂), zirconium (IV) oxide(ZrO₂), aluminum titanium oxide (AlTiO), aluminum zirconium oxide(AlZrO), zinc oxide (ZnO), indium tin oxide (ITO), AlON, SiON, TiON andthe like, having the similar film properties may also be utilized assuch a barrier/blocking layer.

In one example, the precursors used in the ALD process for forming theAl₂O₃ layer includes at least a metal containing precursor, such as analuminum containing gas, and a reacting gas. Suitable examples of thealuminum containing gas may have a formula of R_(x)Al_(y)R′_(z)R″_(v) orR_(x)Al_(y)(OR′)_(z), where R, R′ and R″ are H, CH₃, C₂H₅, C₃H₇, CO,NCO, alkyl or aryl group and x, y, z and v are integers having a rangebetween 1 and 8. In another embodiment, the aluminum containing compoundmay have a formula of Al(NRR′)₃, where R and R′ may be H, CH₃, C₂H₅,C₃H₇, CO, NCO, alkyl or aryl group and R′ may be H, CH₃, C₂H₅, C₃H₇, CO,NCO, alkyl or aryl group. Examples of suitable aluminum containingcompounds are diethylalumium ethoxide (Et₂AlOEt),triethyl-tri-sec-butoxy dialumium (Et₃Al₂OBu₃, or EBDA),trimethylaluminum (TMA), trimethyldialumium ethoxide, dimethyl aluminumisupropoxide, disecbutoxy aluminum ethoxide, (OR)₂AlR′, wherein R, R′and R″ may be methyl, ethyl, propyl, isopropyl, butyl, isobutyl,tertiary butyl, and other alkyl groups having higher numbers of carbonatoms, and the like.

The reacting gas that may be supplied with the aluminum containing gasincludes an oxygen containing gas, such as, oxygen (O₂), ozone (O₃),nitrogen (N₂), N₂O, NO, CO, CO₂ and among others.

It is noted that when the ALD process selected to form the dielectriclayer 112 is a thermal ALD process, the resultant dielectric layer 112tends to have a tensile stress film structure while the resultantdielectric layer 112 tends to have either compressive or tensile stressfilm structure when it is a plasma assisted ALD process based ondifferent process parameters controlled. Thus, in the examples when thestress of the dielectric layer 112 is desired to be adjusted or alteredat different stages of the deposition process, the ALD process asperformed may be switched from thermal ALD to a plasma assisted ALDprocess (or vice versa) or switched process parameters during depositionas needed to adjust tensile/compressive film stress. The refractiveindex of the dielectric layer 112 is desired to be between 1.61 and1.65, such as about 1.63.

After depositing the dielectric layer 112, the buffer layer 114 isdeposited in process 210 as shown in FIG. 3C. The buffer layer 114 maybe HMDSO, such as pp-HMDSO:F, deposited in a PECVD chamber. A firstportion 314 a of the buffer layer 114 is deposited on the substrate 106through the opening 307 of the mask 309 on the region of the substrate106 exposed by the mask 309, covering the first portion 312 a of thedielectric layer 112. A second portion 314 b of the buffer layer 114 isdeposited on the second portion 312 b of the dielectric layer 112disposed on the mask 309, which covers the portion 305 of the contactlayer 108. The buffer layer 114 may have a thickness of between about 2μm to about 5 μm.

In some embodiments, the second dielectric layer 120 may be deposited onthe buffer layer 114 in process 212 as shown in FIG. 3D. A first portion316 a of the dielectric layer 120 is deposited on the substrate 106through the opening 307 of the mask 309 on the region of the substrate106 exposed by the mask 309, covering the first portion 314 a of thebuffer layer 114. A second portion 316 b of the dielectric layer 120 isdeposited on the second portion 314 b of the buffer layer 114 disposedon the mask 309, which covers the portion 305 of the contact layer 108.The dielectric layer 120 may be similar to the dielectric layer 112 andmay be deposited by ALD process, such as plasma assisted ALD.

At process 214, the second barrier layer 116 is formed over thesubstrate 106, covering the dielectric layer 120, as shown in FIG. 3E.The second barrier layer 116 includes a first portion 318 a depositedover the first portion 316 a of the dielectric layer 120 and a secondportion 318 b deposited over the second portion 316 b of the dielectriclayer 120. The second barrier layer 116 may be a dielectric layersimilar to the first barrier layer 110. As shown in FIG. 3E, the TFEstructure 104 may include the first barrier layer 110, the firstdielectric layer 112, the buffer layer 114, the second dielectric layer120, and the second barrier layer 116. Alternatively, the TFE structure104 may include a single dielectric layer as shown in FIGS. 1A, 1B, 1C,or multiple dielectric layers located at different locations within theTFE structure 104.

FIG. 4 is a flow diagram of a method 400 for forming the encapsulatingstructure 104 over the OLED structure 102 according to variousembodiments described herein. FIGS. 5A-5D illustrate schematic crosssectional views of an OLED device 500 during different stages of themethod 400 of FIG. 4. The method 400 starts at process 402 byintroducing the substrate 106 having the preformed OLED structure 102disposed thereon into a processing chamber. The substrate 106 may havethe contact layer 108 disposed thereon, with the OLED structure 102disposed on the contact layer 108, as shown in FIG. 5A.

At process 404, the first barrier layer 122 is deposited on the OLEDstructure 102 and the contact layer 108, as shown in FIG. 5B. Unlike themethod 200, the method 400 does not include the mask 309 covering aportion of the substrate 106. The first barrier layer 122 may be asilicon nitride layer having a thickness of about 1200 Angstroms. Atprocess 406, the first dielectric layer 124 is deposited on the firstbarrier layer 122, as shown in FIG. 5C. The first dielectric layer 124may be deposited by similar method as the dielectric layer 112. In oneembodiment, the first dielectric layer 124 is an Al₂O₃ layer having athickness of about 600 Angstroms. At process 408, the second barrierlayer 126 is deposited on the first dielectric layer 124, as shown inFIG. 5D. The second barrier layer 126 may be a silicon nitride layerhaving a thickness of about 1200 Angstroms. As shown in FIG. 5D, the TFEstructure 104 includes the first barrier layer 122, the first dielectriclayer 124, and the second barrier layer 126. Alternatively, the TFEstructure 104 may further include the second dielectric layer 128 andthe third barrier layer 130, as shown in FIG. 1F.

FIGS. 6A-6C are charts illustrating the benefit of having the TFEstructure 104 shown in FIGS. 1A-1E. FIGS. 6A-6C depicts the dark areapercentage found in the display device plotted as a function of OLEDdisplay device storage time in 60° C./90% relative humidity (RH) or 85°C./85% relative humidity (RH) environment. For FIG. 6A, each trace linesA, B, C indicates different dark area occurrence percentage verse OLEDdisplay device storage time in 85° C./85% relative humidity (RH)environment. Trace line A represents a TFE structure including twobarrier layers, such as barrier layers 110, 116 without an ALDdielectric layer in between. Trace line B represents the TFE structurehaving three layers, including an ALD dielectric layer sandwichedbetween two barrier layers. The ALD dielectric layer may be thedielectric layer 124, the barrier layers may be barrier layers 122, 126.Trance line C represents the TFE structure having five layers, such asthe TFE structure 104 shown in FIG. 1E. As shown in FIG. 6A, the TFEstructure having the ALD dielectric layer formed therein, as indicatedin trace line B and C, slows down the occurrence of the dark area on thedisplay device. Thus, by utilizing the ALD dielectric layer in the TFEstructure, the dark area occurrence rate is significantly reducedcompared to the TFE structure without the ALD dielectric layer under thesame amount of OLED display storage time in 85° C./85% relative humidity(RH) environment, thus efficiently increasing the service life time ofthe display device.

FIG. 6B also illustrates dark area percentages versus display devicestorage time in 60° C./90% relative humidity (RH) environment for fourTFE structures used in an OLED device. Trace line A represents the TFEstructure 104 shown in FIG. 1B, and the dielectric layer 118 has athickness of about 300 Angstroms, the first barrier layer 110 has athickness of about 2500 Angstroms, the buffer layer 114 has a thicknessof about 1 micron, and the thickness of the second barrier layer 116 hasa thickness of about 2500 Angstroms. Trance line B represents the TFEstructure 104 shown in FIG. 1A, and the first barrier layer 110 has athickness of about 2500 Angstroms, the dielectric layer 112 has athickness of about 300 Angstroms, the buffer layer 114 has a thicknessof about 1 micron, and the second barrier layer 116 has a thickness ofabout 2500 Angstroms. Trace line C represents the TFE structure 104shown in FIG. 1C, and the first barrier layer 110 has a thickness ofabout 2500 Angstroms, the buffer layer 114 has a thickness of about 1micron, the dielectric layer 120 has a thickness of about 300 Angstroms,and the second barrier layer 116 has a thickness of about 2500Angstroms. Trace line D represents the TFE structure 104 shown in FIG.1D, and the first barrier layer 110 has a thickness of about 2500Angstroms, the buffer layer 114 has a thickness of about 1 micron, thesecond barrier layer 116 has a thickness of about 2500 Angstroms, andthe dielectric layer 121 has a thickness of about 300 Angstroms. Asshown in FIG. 6B, trace line B shows the longest operating time withoutdark area. In addition, all of the trace lines A, B, C, D show that forabout 150 hours there are very small percentages of dark area. Comparingto trace line A in FIG. 6A, for the TFE structure does not include theALD dielectric layer, there is about 60% of dark area at about 150hours. Thus, by utilizing the ALD dielectric layer in the TFE structure,the dark area occurrence rate is significantly reduced compared to theTFE structure without the ALD dielectric layer under the same amount ofOLED display operation time, thus efficiently increasing the servicelife time of the display device.

FIG. 6C also illustrates dark area percentages versus device storagetime in 60 C/90 relative humidity (RH) environment for three TFEstructures used in an OLED device. Trace line A represents a TFEstructure including a 1.5 micron thick buffer layer, such as the bufferlayer 114, sandwiched between two 300 Angstroms thick dielectric layers,such as dielectric layers 112, 120. Trace line B represents the TFEstructure 104 shown in FIG. 1A, and the first barrier layer 110 has athickness of about 7500 Angstroms, the dielectric layer 112 has athickness of about 300 Angstroms, the buffer layer 114 has a thicknessof about 1.5 micron, and the second barrier layer 116 has a thickness ofabout 7500 Angstroms. Trace line C represents the TFE structure 104shown in FIG. 1A, and the first barrier layer 110 has a thickness ofabout 2500 Angstroms, the dielectric layer 112 has a thickness of about300 Angstroms, the buffer layer 114 has a thickness of about 1.5 micron,and the second barrier layer 116 has a thickness of about 7500Angstroms. As shown in FIG. 6C, trace line B shows the best barrierperformance, i.e., has the longest life time without dark areaformation.

FIG. 7 is a schematic, cross sectional view of a PECVD chamber 700 thatmay be used to perform the operations described herein. One or morefilms may be deposited onto a substrate 720 placed inside the PECVDchamber 700. The chamber 700 generally includes walls 702, a bottom 704and a showerhead 706 which define a process volume. A substrate support718 is disposed within the process volume. The process volume isaccessed through a slit valve opening 708 such that the substrate 720may be transferred in and out of the chamber 700. The substrate support718 is coupled to an actuator 716 to raise and lower the substratesupport 718. Lift pins 722 are moveably disposed through the substratesupport 718 to move the substrate 720 to and from the substratereceiving surface. The substrate support 718 also includes heatingand/or cooling elements 724 to maintain the substrate support 718 at apredetermined temperature. The substrate support 718 also includes RFreturn straps 726 to provide an RF return path at the periphery of thesubstrate support 718.

The showerhead 706 is coupled to a backing plate 712 by a fasteningmechanism 750. The showerhead 706 is coupled to the backing plate 712 byone or more fastening mechanisms 750 to help prevent sag and/or controlthe straightness/curvature of the showerhead 706.

A gas source 732 is coupled to the backing plate 712 to provide gasthrough gas passages in the showerhead 706 to a processing area betweenthe showerhead 706 and the substrate 720. A vacuum pump 710 is coupledto the chamber 700 to maintain the process volume at a predeterminedpressure. An RF source 728 is coupled through a match network 790 to thebacking plate 712 and/or to the showerhead 706 to provide an RF currentto the showerhead 706. The RF current creates an electric field betweenthe showerhead 706 and the substrate support 718 so that a plasma may begenerated from the gases between the showerhead 706 and the substratesupport 718.

A remote plasma source 730, such as an inductively coupled remote plasmasource 730, is coupled between the gas source 732 and the backing plate712. Between processing substrates, a cleaning gas may be provided tothe remote plasma source 730 so that a remote plasma is generated. Theradicals from the remote plasma may be provided to chamber 700 to cleanchamber 700 components. The cleaning gas may be further excited by theRF source 728 provided to the showerhead 706.

The showerhead 706 is additionally coupled to the backing plate 712 byshowerhead suspension 734. In one embodiment, the showerhead suspension734 is a flexible metal skirt. The showerhead suspension 734 may have alip 736 upon which the showerhead 706 may rest. The backing plate 712may rest on an upper surface of a ledge 714 coupled with the chamberwalls 702 to seal the chamber 700.

FIG. 8 is a schematic cross sectional view of an ALD chamber 800 thatmay be used to perform the operations described herein. The chamber 800generally includes a chamber body 802, a lid assembly 804, a substratesupport assembly 806, and a process kit 850. The lid assembly 804 isdisposed on the chamber body 802, and the substrate support assembly 806is at least partially disposed within the chamber body 802. The chamberbody 802 includes a slit valve opening 808 formed in a sidewall thereofto provide access to the interior of the processing chamber 800. In someembodiments, the chamber body 802 includes one or more apertures thatare in fluid communication with a vacuum system (e.g., a vacuum pump).The apertures provide an egress for gases within the chamber 800. Thevacuum system is controlled by a process controller to maintain apressure within the ALD chamber 800 suitable for ALD processes. The lidassembly 804 may include one or more differential pumps and purgeassemblies 820. The differential pump and purge assemblies 820 aremounted to the lid assembly 804 with bellows 822. The bellows 822 allowthe pump and purge assemblies 820 to move vertically with respect to thelid assembly 804 while still maintaining a seal against gas leaks. Whenthe process kit 850 is raised into a processing position, a compliantfirst seal 886 and a compliant second seal 888 on the process kit 850are brought into contact with the differential pump and purge assemblies820. The differential pump and purge assemblies 820 are connected with avacuum system (not shown) and maintained at a low pressure.

As shown in FIG. 8, the lid assembly 804 includes a RF cathode 810 thatcan generate a plasma of reactive species within the chamber 800 and/orwithin the process kit 850. The RF cathode 810 may be heated by electricheating elements (not shown), for example, and cooled by circulation ofcooling fluids, for example. Any power source capable of activating thegases into reactive species and maintaining the plasma of reactivespecies may be used. For example, RF or microwave (MW) based powerdischarge techniques may be used. The activation may also be generatedby a thermally based technique, a gas breakdown technique, a highintensity light source (e.g., UV energy), or exposure to an x-raysource.

The substrate support assembly 806 can be at least partially disposedwithin the chamber body 802. The substrate support assembly 806 caninclude a substrate support member or susceptor 830 to support asubstrate 832 for processing within the chamber body. The susceptor 830may be coupled to a substrate lift mechanism (not shown) through a shaft824 or shafts 824 which extend through one or more openings 826 formedin a bottom surface of the chamber body 802. The substrate liftmechanism can be flexibly sealed to the chamber body 802 by a bellows828 that prevents vacuum leakage from around the shafts 824. Thesubstrate lift mechanism allows the susceptor 830 to be moved verticallywithin the ALD chamber 800 between a lower robot entry position, asshown, and processing, process kit transfer, and substrate transferpositions. In some embodiments, the substrate lift mechanism movesbetween fewer positions than those described.

In some embodiments, the substrate 832 may be secured to the susceptorusing a vacuum chuck (not shown), an electrostatic chuck (not shown), ora mechanical clamp (not shown). The temperature of the susceptor 830 maybe controlled (by, e.g., a process controller) during processing in theALD chamber 800 to influence temperature of the substrate 832 and theprocess kit 850 to improve performance of the ALD processing. Thesusceptor 830 may be heated by, for example, electric heating elements(not shown) within the susceptor 830. The temperature of the susceptor830 may be determined by pyrometers (not shown) in the chamber 800, forexample.

As shown in FIG. 8, the susceptor 830 can include one or more bores 834through the susceptor 830 to accommodate one or more lift pins 836. Eachlift pin 836 is mounted so that they may slide freely within a bore 834.The support assembly 806 is movable such that the upper surface of thelift pins 836 can be located above the substrate support surface 838 ofthe susceptor 830 when the support assembly 806 is in a lower position.Conversely, the upper surface of the lift pins 836 is located below theupper surface 838 of the susceptor 830 when the support assembly 806 isin a raised position. When contacting the chamber body 802, the liftpins 836 push against a lower surface of the substrate 832, lifting thesubstrate off the susceptor 830. Conversely, the susceptor 830 may raisethe substrate 832 off of the lift pins 836.

In some embodiments, the susceptor includes process kit insulationbuttons 837 that may include one or more compliant seals 839. Theprocess kit insulation buttons 837 may be used to carry the process kit850 on the susceptor 830. The one or more compliant seals 839 in theprocess kit insulation buttons 837 are compressed when the susceptorlifts the process kit 850 into the processing position.

FIG. 9 illustrates an exemplary reactive sputter processing chamber 900suitable for metal containing material. The processing chamber 900 maybe part of a vacuum processing system 1000 having multiple processingchambers, which will be described latter below. One example of theprocess chamber that may be adapted to benefit from the disclosure is aphysical vapor deposition (PVD) process chamber, available from AppliedMaterials, Inc., located in Santa Clara, Calif. It is contemplated thatother sputter process chambers, including those from other manufactures,may be adapted to practice the present invention.

The processing chamber 900 includes a chamber body 908 having aprocessing volume 918 defined therein and enclosed by a lid assembly904. The chamber body 908 has sidewalls 910 and a bottom 946. Thedimensions of the chamber body 908 and related components of the processchamber 900 are not limited and generally are proportionally larger thanthe size of a substrate, to be processed therein. As such, any suitablesubstrate size may be processed in a suitable sized process chamber.Examples of suitable substrate sizes include substrates having a plansurface area of about 2000 or more square centimeters.

The chamber body 908 may be fabricated from aluminum or other suitablematerial. A substrate access port 930 is formed through the sidewall 910of the chamber body 908, facilitating the transfer of the substrate 902(i.e., a flat panel display substrate or a solar panel, a plastic orflexible substrate, a semiconductor wafer, or other workpiece) into andout of the process chamber 900. The access port 930 may be coupled to atransfer chamber and/or other chambers of a substrate processing system.

A gas source 928 is coupled to the chamber body 908 to supply processgases into the processing volume 918. Examples of process gases that maybe provided by the gas source 928 include inert gases, non-reactivegases, and reactive gases. In one embodiment, process gases provided bythe gas source 928 may include, but not limited to, argon gas (Ar),helium (He), nitrogen gas (N₂), oxygen gas (O₂), and H₂O, among others.

A pumping port 950 is formed through the bottom 946 of the chamber body908. A pumping device 952 is coupled to the process volume 918 toevacuate and control the pressure therein. In one embodiment, thepressure level of the process chamber 900 may be maintained at about 1Torr or less.

The lid assembly 904 generally includes a target 920 and a ground shieldassembly 926 coupled or positioned proximate thereto. The target 920provides a material source that can be sputtered and deposited onto thesurface of the substrate 902 during a PVD process. The target 920 ortarget plate may be fabricated from a material utilized as a depositionspecie. A high voltage power supply, such as a power source 932, isconnected to the target 920 to facilitate sputtering materials from thetarget 920. In one embodiment, the target 920 may be fabricated from ametal containing material, such as titanium (Ti), tantalum (Ta),aluminum oxide (Al₂O₃), magnesium (Mg), silver (Si), indium (In), tin(Sn), indium tin oxide (ITO), indium tin oxide (ITO), indium zinc oxide(IZO), indium tin zinc oxide (ITZO), aluminum (Al), tungsten (W), gold(Au), molybdenum (Mo), mercury (Hg), chromium (Cr), metal, metal alloyor other suitable materials. In another embodiment, the target 920 maybe fabricated by materials including indium tin alloy and the like.

The target 920 generally includes a peripheral portion 924 and a centralportion 916. The peripheral portion 924 is disposed over the sidewalls910 of the chamber 900. The central portion 916 of the target 920 mayhave a curvature surface slightly extending towards the surface of thesubstrate 902 disposed on a substrate support 938. The spacing betweenthe target 920 and the substrate support 938 is maintained between about50 mm and about 150 mm. It is noted that the dimension, shape,materials, configuration and diameter of the target 920 may be variedfor specific process or substrate requirements. In one embodiment, thetarget 920 may further include a backing plate having a central portionbonded and/or fabricated from a material desired to be sputtered ontothe substrate surface. The target 920 may also include a plurality oftiles or segment materials that together form the target.

The lid assembly 904 may further comprise a magnetron assembly 901mounted above the target 920 which enhances efficient sputtering ofmaterial from the target 920 during processing. Examples of themagnetron assembly include a linear magnetron, a serpentine magnetron, aspiral magnetron, a double-digitated magnetron, a rectangularized spiralmagnetron, among others.

The ground shield assembly 926 of the lid assembly 904 includes a groundframe 906 and a ground shield 912. The ground shield assembly 926 mayalso include other chamber shield members, target shield member, darkspace shield, and dark space shield frame. The ground shield 912 iscoupled to the peripheral portion 924 by the ground frame 906 definingan upper processing region 954 below the central portion 916 of thetarget 920 in the process volume 918. The ground frame 906 electricallyinsulates the ground shield 912 from the target 920 while providing aground path to the chamber body 908 of the process chamber 900 throughthe sidewalls 910. The ground shield 912 constrains plasma generatedduring processing within the upper processing region 954 so thatdislodged target source material from the central portion 916 of thetarget 920 is mainly deposited on the substrate surface rather thanchamber sidewalls 910. In one embodiment, the ground shield 912 may beformed by one or more components.

A shaft 940 that extends through the bottom 946 of the chamber body 908couples the substrate support 938 to a lift mechanism 944. The liftmechanism 944 is configured to move the substrate support 938 between alower transfer position and an upper processing position. A bellows 942circumscribes the shaft 940 and is coupled to the substrate support 938to provide a flexible seal therebetween, thereby maintaining vacuumintegrity of the chamber processing volume 918.

A shadow frame 922 is disposed on the periphery region of the substratesupport 938 and is configured to confine deposition of source materialsputtered from the target 920 to a desired portion of the substratesurface. When the substrate support 938 is in a lowered position, theshadow frame 922 is suspended above the substrate support 938 from a lip956 of a chamber shield 936 that extends from the sidewall 910 of thechamber body 908. As the substrate support 938 is raised to the upperposition for processing, an outer edge of the substrate 902 disposed onthe substrate support 938 contacts the shadow frame 922, causing theshadow frame 922 to be lifted and spaced away from the chamber shield936. In or while moving into the lowered position, lift pins (not shown)are selectively moved through the substrate support 938 to lift thesubstrate 902 above the substrate support 938 to facilitate access tothe substrate 902 by a transfer robot or other suitable transfermechanism.

A controller 948 is coupled to the processing chamber 900 and,optionally, the processing chamber 900. The controller 948 includes acentral processing unit (CPU) 260, a memory 958, and support circuits962. The controller 948 is utilized to control the process sequence,regulating the gas flows from the gas source 928 into the chamber 900and controlling ion bombardment of the target 920. The CPU 960 may be ofany form of a general purpose computer processor that can be used in anindustrial setting. The software routines can be stored in the memory958, such as random access memory, read only memory, floppy or hard diskdrive, or other form of digital storage. The support circuits 962 areconventionally coupled to the CPU 960 and may comprise cache, clockcircuits, input/output subsystems, power supplies, and the like. Thesoftware routines, when executed by the CPU 960, transform the CPU intoa specific purpose computer (controller) 948 that controls theprocessing chamber 900 such that the processes are performed inaccordance with the present invention. The software routines may also bestored and/or executed by a second controller (not shown) that islocated remotely from the chamber 900.

During processing, the target 920 and the substrate support 938 arebiased relative to each other by the power source 932 to maintain aplasma formed from the process gases supplied by the gas source 928. Theions from the plasma are accelerated toward and strike the target 920,causing target material to be dislodged from the target 920. Thedislodged target material forms a layer on the substrate 902. Inembodiments where certain process gases are supplied into the chamber900, the dislodged target material and the process gases present in thechamber 900 react to forms a composite film on the substrate 902.

FIG. 10 is a top plan view of a multi-chamber substrate processingsystem 1000 suitable for the fabrication of organic light emittingdiodes (OLEDS), thin-film transistors (TFT), and solar cell fabricationon flat media. The system 1000 includes a plurality of processingchambers 700, 800, 900, 1500 and one or more load lock chambers 1005,1007 positioned around a central transfer chamber 1015. The processingchambers 700, 800, 900, 1500 may be configured to complete a number ofdifferent processing steps to achieve a desired processing of flatmedia, such as a large area substrate 1006 (outlined in dashed lines).The load lock chambers 1005, 1007 are configured to transfer a substratein a quadrilateral form from an ambient environment outside themulti-chamber substrate processing system 1000 to a vacuum environmentinside the transfer chamber 1015.

Positioned within the transfer chamber 1015 is a transfer robot 1025having an end effector 1030. The end effector 1030 is configured to besupported and move independently of the transfer robot 1025 to transferthe substrate 1006. The end effector 1030 includes a wrist 1035 and aplurality of fingers 1040 adapted to support the substrate 1006. In oneembodiment, the transfer robot 1025 is configured to be rotated about avertical axis and/or linearly driven in a vertical direction (Zdirection) while the end effector 1030 is configured to move linearly ina horizontal direction (X and/or Y direction) independent of andrelative to the transfer robot 1025. For example, the transfer robot1025 raises and lowers the end effector 1030 (Z direction) to variouselevations within the transfer chamber 1015 to align the end effector1030 with openings in the processing chambers 700, 800, 900, 1500 andthe load lock chambers 1005, 1007. When the transfer robot 1025 is at asuitable elevation, the end effector 1030 is extended horizontally (X orY direction) to transfer and/or position the substrate 1006 into and outof any one of the processing chambers 700, 800, 900, 1500 and the loadlock chambers 1005, 1007. Additionally, the transfer robot 1025 may berotated to align the end effector 1030 with other processing chambers700, 800, 900, 1500 and the load lock chambers 1005, 1007.

In one example, the processing chambers 700, 800, 900, 1500 incorporatedin the multi-chamber substrate processing system 1000 may be the plasmaenhanced chemical vapor deposition (PECVD) chamber 700 depicted in FIG.7, the atomic layer deposition (ALD) chamber 800 depicted in FIG. 8, orthe physical vapor deposition (PVD) chamber 900 depicted in FIG. 9 orother suitable chambers, such as HDP-CVD, thermal annealing, surfacetreatment, electron beam (e-beam) treatment, plasma treatment, etchingchambers, ion implantation chambers, surface cleaning chamber, metrologychambers, spin-coating chamber, polymer spinning deposition chamber orany suitable chambers as needed. In one example depicted in themulti-chamber substrate processing system 1000, the system 1000 includesthe chemical vapor deposition (such as a PECVD) chamber 700, the atomiclayer deposition (ALD) chamber 800, the physical vapor deposition (PVD)chamber 900 and other suitable chambers 1500 as needed. By sucharrangement, the dielectric layer 112, 118, 120, 121, 124, 128 formed bythe ALD process, the barrier layer 110, 116, 122, 126, 130 formed by thePECVD process, or the buffer layer 114 formed by a CVD process or aspin-coating process may also be integrated to perform in a singlechamber without breaking vacuum so as to maintain cleanliness of thesubstrate without undesired contamination and residuals from theenvironment.

A portion of the interior of load lock chamber 1005 has been removed toexpose a substrate support or susceptor 1050 that is adapted to receiveand support the large area substrate 1006 during processing. Thesusceptor 1050 includes a plurality of lift pins 1055 that are movablerelative to an upper surface of the susceptor 1050 to facilitatetransfer of the large area substrate 1006. In one example of a transferprocess of the large area substrate 1006, the lift pins 1055 areextended away from or above the upper surface of the susceptor 1050. Theend effector 1030 extends in the X direction into the processing chamber700, 800, 900, 1500 or load lock chambers 1005, 1007 above the extendedlift pins. The transfer robot 1025 lowers the end effector 1030 in the Zdirection until the large area substrate 1006 is supported by the liftpins 1055. The lift pins 1055 are spaced to allow the fingers 1040 ofthe end effector 1030 to pass the lift pins 1055 without interference.The end effector 1030 may be further lowered to assure clearance betweenthe large area substrate 1006 and the fingers 140 and the end effector1030 is retracted in the X direction into the transfer chamber 1015. Thelift pins 1055 may be retracted to a position that is substantiallyflush with the upper surface of the susceptor 1050 in order to bring thelarge area substrate 1006 into contact with the susceptor 1050 so thesusceptor 1050 supports the large area substrate 1006. A slit valve ordoor 1060 between the transfer chamber 1015 and the load lock chamber1005, 1007 (or the processing chamber or 700, 800, 900, 1500) may besealed and processing may be commenced in the load lock chamber 1005,1007 (or the processing chamber or 700, 800, 900, 1500). To remove thelarge area substrate 1006 after processing, the transfer process may bereversed, wherein the lift pins 1055 raise the large area substrate 1006and the end effector 1030 may retrieve the large area substrate 1006. Inone example, the substrate 1006 may be transferred into themulti-chamber substrate processing system 1000 through the first loadlock chamber 1005. After the substrate 1006 is oriented and aligned to adesired position, the substrate 1006 is then transferred to any one ofthe processing chambers 700, 800, 900, 1500 through the transfer chamber1015 to perform any suitable processes as needed to form a devicestructure on the substrate 1006. After the processes are completed inthe processing chambers 700, 800, 900, 1500, then the substrate 1006 isremoved from and transferred out of the multi-chamber substrateprocessing system 1000 from the second load lock chamber 1007 as needed.

The environment in the substrate processing system 1000 is isolated fromambient pressure (i.e. pressure outside the system 1000) and ismaintained at a negative pressure by one or more vacuum pumps (notshown). During processing, the processing chambers 700, 800, 900, 1500are pumped down to pre-determined pressures configured to facilitatethin film deposition and other processes. Likewise, the transfer chamber1015 is held at a reduced pressure during transfer of the large areasubstrates to facilitate a minimal pressure gradient between theprocessing chambers 700, 800, 900, 1500 and the transfer chamber 1015.In one embodiment, the pressure in the transfer chamber 1015 ismaintained at a pressure lower than ambient pressure. For example, thepressure in the transfer chamber may be about 7 Torr to about 10 Torrwhile the pressure in the processing chambers 700, 800, 900, 1500 may belower. In one embodiment, the maintained pressure within the transferchamber 1015 may be substantially equal to the pressure within theprocessing chambers 700, 800, 900, 1500 and/or load lock chambers 1005and 1007 to facilitate a substantially equalized pressure in the system1000

During the transfer of the large area substrate 1006 in the transferchamber 1015 and the processing chambers 700, 800, 900, 1500, properalignment of the large area substrate 1006 is crucial to preventcollisions and/or damage of the large area substrate 1006. Additionally,the interior of the system 1000 must be kept clean and free from debrissuch as broken pieces of a substrate, broken equipment, and otherparticulate contamination. While some conventional systems include viewwindows allowing line of sight viewing into the interior of the variouschambers 700, 800, 900, 1500, the windows may not allow a full viewand/or precise inspection of the large area substrates and the interiorof the various chambers 700, 800, 900, 1500. Also, the conventionalsystems are not configured to view the large area substrate 1006 andprovide a metric of processing results while the large area substratesare in the system.

The transfer robot 1025 includes one or more optical image sensors 1065and 1070 disposed on the transfer robot 1025 as needed. The one or moreoptical image sensors 1065, 1070 may be optical scanners, imagers orcameras, such as a charged-coupled device (CCD), a complimentary metaloxide semiconductor (CMOS) device, a video camera, and the like. In oneembodiment, one or more of the optical image sensors 1065, 1070 aremounted on the transfer robot 1025 in a position to view the large areasubstrate 1006, the fingers 1040 and any object in the line of sightview of the sensors 1065, 1070. In this embodiment, the image sensors1065, 1070 may be oriented to view objects substantially in the X and Ydirection as well as the Z direction as the transfer robot 1025 isstationary or moving in the system 1000. The image sensors 1065, 1070may include wide angle optics, such as a fisheye lens, to enable agreater field of view.

In summary, an OLED structure is encapsulated by a TFE structure. TheTFE structure includes a dielectric layer formed by ALD and at least twobarrier layers. By including an additional dielectric layer formed byALD in the TFE structure, the barrier performance of the TFE structureis improved.

While the foregoing is directed to embodiments of the presentdisclosure, other and further embodiments of the disclosure may bedevised without departing from the basic scope thereof, and the scopethereof is determined by the claims that follow.

The invention claimed is:
 1. A thin film encapsulation structure,comprising: a first barrier layer formed on a substrate having an OLEDstructure, wherein the first barrier layer is in direct contact with theOLED structure, the first barrier layer is fabricated by a chemicalvapor deposition process; a first dielectric layer in direct contactwith en the first barrier layer, wherein the first dielectric layer isformed by an atomic layer deposition process; a second barrier layerdisposed on the first dielectric layer; and a second dielectric layerdisposed on the second barrier layer.
 2. The thin film encapsulationstructure of claim 1, wherein the first and second barrier layers arefabricated from substantially the same material.
 3. The thin filmencapsulation structure of claim 2, wherein the first dielectric layeris a metal dielectric layer.
 4. The thin film encapsulation structure ofclaim 3, wherein the metal dielectric layer is selected from the groupconsisting of aluminum oxide (Al₂O₃), titanium oxide (TiO₂), zirconium(IV) oxide (ZrO₂), aluminum titanium oxide (AlTiO), aluminum zirconiumoxide (AlZrO), zinc oxide (ZnO), indium tin oxide (ITO), AlON, SiON andAlN.
 5. The thin film encapsulation structure of claim 1, furthercomprising a buffer layer disposed between the first dielectric layerand the second barrier layer.
 6. The thin film encapsulation structureof claim 5, wherein the buffer layer is organic.
 7. The thin filmencapsulation structure of claim 5, wherein the buffer layer is ahexamethyldisiloxane layer.
 8. The thin film encapsulation structure ofclaim 1, wherein the second dielectric layer is formed by an atomiclayer deposition process.
 9. The thin film encapsulation structure ofclaim 1, wherein the first and second barrier layers are inorganic. 10.The thin film encapsulation structure of claim 1, wherein the first andsecond dielectric layers are inorganic.
 11. The thin film encapsulationstructure of claim 1, further comprising: a third dielectric layerformed between the first dielectric layer and the second barrier layer.12. The thin film encapsulation structure of claim 1, wherein the secondbarrier layer is formed by a chemical vapor deposition process.
 13. Thethin film encapsulation structure of claim 1, further comprising: athird barrier layer disposed on the second dielectric layer.
 14. Thethin film encapsulation structure of claim 13, wherein the first, secondand third barrier layers are selected from the group consisting ofsilicon nitride (SiN), silicon oxynitride (SiON), silicon dioxide(SiO₂), aluminum oxide (Al₂O₃) and aluminum nitride (AlN).
 15. The thinfilm encapsulation structure of claim 1, wherein the first dielectriclayer is aluminum oxide (Al₂O₃).